Microbiology-Vaccine Preventable Bacterial Diseases of Childhood Flashcards
Passive immunization
Transfer of pre-formed antibody by IV Ig (TIG for tetanus) or antitoxin (botulism and diphtheria)
Active immunization
Stimulation of the host immune response by vaccination or natural infection and antibody formation.
Toxoid
Toxin preparation that stimulates formation of antitoxin
What type of vaccines are BCG for tuberculosis and Ty21A for typhoid?
Live, attenuated vaccines.
What type of vaccines are tetanus, diphtheria and anthrax?
Toxoid vaccines
What type of vaccines are the old pneumococcal 23 valent and meningococcal 4 valent?
Polysaccharide alone
What type of vaccines are Hib, the 13 valent pneumococcal and 4 valent meningococcal?
Conjugate
Why do children < 2 years of age need the conjugate pneumococcal vaccine?
Polysaccharides are T-independent antigens, which are not recognized by the immune system of children less than 2 years of age and you get mostly and IgM response. With the conjugate vaccine you activate T cells which produces IgG antibodies and memory plasma cells that results in lasting immunity.
Most likely population affected by bordetella pertussis
Children < 1 year old are at highest risk for whooping cough
A child presents with whooping cough. What would you expect lab results to look like?
Bordetella pertussis is a gram negative, pleomorphic, short coccobacilli that grow on Bordet-Gengou agar or Regan-Lowe charcoal medium with horse blood (isolate fatty acids b/c fatty acids are toxic to bordetella).
What are the virulence factors associated with bordetella pertussis?
Pertussis toxin (LPF): activates membrane and extracellular adenlylate cyclase via Gi protein -> increases cAMP -> fluid secretion in upper respiratory tract. Filamentous hemagglutinin: adhesion. Tracheal cytotoxin: looks like a fragmented cell wall and destroys ciliated epithelial cells.
Why might the lab be scared that someone has leukemia when they really have pertussis?
Bordetella pertussis causes an intense lymphocytosis.
Steps of pertussis infection
1) Colonization w/o invasion of respiratory epithelium (by filamentous hemagglutinin and pertactin 2) Local damage by tracheal cytotoxin 3) Impaired immune response by extracellular adenylate cyclase activation 4) Systemic lymphocytosis due to pertussis toxin
Difference between the old wholesale pertussis vaccine and the acellular vaccine?
The acellular vaccine prevents symptoms by neutralization of toxin, but not infection because there is no antibody response against the adhesins. The old vaccine prevents colonization.
Stages of pertussis
1) 7–10 day incubation w/no symptoms 2) 2-4 week catarrhal stage w/fever, malaise, runny nose 3) 2-4 week paroxysmal stage with whooping cough, vomiting and leukocytosis 4) 3-4 week convalescent stage with secondary complications like pneumonia, seizure and encephalopathy.
What type of disease is diphtheria?
Toxin-mediated disease. Diphtheria toxin has a binding subunit (B) and an active subunit (A) that ADP-ribosylates EF-2 and inhibits protein synthesis.
